Various techniques have been used to connect either header plates or cap members to shells of heat exchangers without the use of soldering or welding. For example, the U.S. Pat. Nos. 4,360,060 to Collgon, issued Nov. 23, 1982, and 4,485,867 to Melnyk et al, issued Dec. 4, 1984, disclose heat exchangers of the type including rows of tubes and a pair of headers secured to the ends of the tubes by the headers being crimped around the end of the shell or housing member. In the Melnyk et al patent, a tank is lowered onto a header and gasket such that a blunt-nosed edge is adapted to force the center portion of the gasket into a depression formed in the bottom of the center of grooves in the header. Once the tank is positioned in this manner, the peripheral wall portions of the header member is folded over onto a ledge on the tank. In the Collgon patent, the peripheral edge of the cap member has a U-shaped edge when viewed in cross section for fitting over a water box.
The U.S. Pat. Nos. 4,305,459 to Nonnenmann et al, issued Dec. 15, 1981 and 4,600,051 to Wehrman, issued July 15, 1987, disclose heat exchangers having solderless connections wherein a gasket is clamped between the flat faces of a edge of a tank and a substantially U-shaped portion of a cap member, the U-shaped portion of the cap member being crimped around an expanded edge of the tank.
The U.S. Pat. Nos. 4,331,201 to Hesse, issued May 25, 1982, and 4,546,823 to Melnyk, issued Oct. 15, 1985 and assigned to the assignee of the present invention, disclose a solderless clamp connection for a heat exchange type assembly wherein a housing is clamped to a header by corrugated interlocking tabs.
It remains desirable to provide a solderless and weldless connection in order to save costs. However, it is desirable to provide a connection of much simpler construction than the prior art while continuing to perfect a seal between the shell or housing of the heat exchanger and the end of the cap member. Further, it is desirable to perfect a seal between the cap member and the header member in an assembly wherein a header is disposed within the shell or housing for supporting a plurality of tubes therein and a cap member is disposed over the end of the housing.
An additional consideration is the use of material having different coefficients of thermal expansion to comprise the shell and heat exchange elements. In an assembly that has been soldered, brazed, or welded any difference in thermal expansion or contraction places undue stresses upon the components and joints. The present invention provides means for absorbing the differences in rate of thermal expansion of the heat exchange element and the outer shell.